Around the turn of 2022, grids of green, yellow and grey squares suddenly filled social media. People were showing off how many guesses they had needed for the day’s word. Within weeks, Wordle had spread around the world. The idea itself was not new, though. Guessing a hidden word or code from feedback goes back decades, through games on paper, games with pegs and games on television.
Bulls and Cows
The oldest of these games needs only a pencil. It is called Bulls and Cows. One player thinks of a four-digit number with all digits different, and the other guesses. After each guess, the guesser learns how many digits are in the right place, the bulls, and how many are in the number but elsewhere, the cows. They are not told which digits those are.
Nobody knows exactly when the game began. Wikipedia’s article on Mastermind says Bulls and Cows may be a century old. It spread by word of mouth rather than through rule books.
Jotto, 1955
Morton M. Rosenfeld swapped digits for letters. In 1955 he invented Jotto, which his New York company, Jotto Corp., sold. Each player secretly writes down a five-letter dictionary word. They then take turns guessing each other’s word. After each guess, the player only learns how many letters the guess shares with the secret word, regardless of position.
Jotto is harder than today’s games, because you do not know which letters you hit. You have to work it out over several guesses. It takes vocabulary and logic in equal measure.
Mastermind, 1970
In 1970 Mordecai Meirowitz, an Israeli postmaster and telecommunications expert, invented the board game Mastermind. It was based on Bulls and Cows, but used coloured pegs instead of numbers. One player hides a row of four colours and the other tries to guess it. A black peg means a right colour in the right place, a white peg a right colour in the wrong place.
The rights were bought by Invicta Plastics, a company based near Leicester, which released the game in 1971 and 1972. Mastermind became a worldwide hit and caught the attention of mathematicians too. In 1976 Donald Knuth showed that with four positions and six colours, the code can always be cracked in five moves or fewer.
Lingo on television
Television took the next step. The American game show Lingo, created by Ralph Andrews, first aired on 28 September 1987. Contestants guessed five-letter words and were given the first letter in advance. A letter in the right place lit up red, a letter that was in the word but elsewhere lit up yellow.
Lingo became especially popular in the Netherlands. The Dutch version ran from 1989 to 2014 and returned from 2019 to 2023. Lingo already had everything we know from today’s games: a fixed word length, a limited number of guesses and coloured feedback for every letter.
Wordle
The software engineer Josh Wardle built his first prototype of the game back in 2013. He made it for himself and his partner, Palak Shah. Shah sorted through roughly 13,000 five-letter English words and picked about 2,000 familiar ones, enough for about five years of daily puzzles.
Wardle finished the prototype in 2014 but put it aside. By January 2021 the game was on the web, but only he and Shah were playing it. He released it publicly in October 2021. The rules were simple: one word a day, the same for everyone, six guesses and coloured tiles. It ran straight in the browser.
The growth was steep. On 1 November 2021, 90 people played. By 2 January 2022 it was more than 300,000, and a week later more than two million. Sharing played a big part. The game gained an option to copy your result as a grid of coloured squares without the letters, and in late December 2021 that helped it spread across Twitter. Everyone could show how they had done without giving the word away.
On 31 January 2022 The New York Times bought the game for a price it described as in the low seven figures. Wordle has been part of the paper’s games ever since.
Why it works
All of these games share the same principle. After each guess, the player gets just enough information to reason with, but not enough to make the answer obvious. Wordle added two things the older games lacked. One word a day for everyone gave people something to talk about, and since you cannot play endlessly, it does not wear out.
According to Wikipedia, Wardle drew on Mastermind for the coloured marking of letters. Jotto and Lingo are similar to Wordle both in idea and in style.
Word games in other languages
After Wordle’s success, dozens of versions appeared in other languages. Slovak and Czech pose their own problems: longer words, many forms of each word and letters with accents.
Daily Word on HoyHop has its own answers to these, in English too. The length of the word changes between five and seven letters, and you always get one guess more than the word has letters. The answer is always a common noun in its basic form, spelled the same in American and British English. The tiles are not green and yellow as in Wordle, but dark and yellow, and every state has its own mark so that people who find colours hard to tell apart can still play.
The exact rules are in Daily Word rules in detail, and advice on guessing better in Daily Word tips: first words and next guesses.